Heat exchanger

ABSTRACT

A heat exchanger of the tube-and-shell type is equipped with a tube bundle eccentric relative to the upright axis of the shell. The upper part of the tube bundle is enveloped by a cylindrical, coaxial skirt depending from the fixed, upper tube sheet. Steam is admitted to the widest portion of the crescent-shaped, annular space between the shell and the skirt and deflected to ward the lower ends of the tubes. The non-condensable gases are vented near the axis of the bundle. Partitions in the liquid chambers or heads cause the liquid to be heated to flow downward in the tube nearest the common axis of the bundle and skirt and thereafter alternatingly upward and downward in tubes gradually more remote from the axis of the bundle.

United States Patent [191 Credoz et a1.

[ HEAT EXCHANGER [75] Inventors: Paul Credoz, Denain; Jacques de Cremoux, Douchy Les Mines; Jacques Gaffet, Denain, all of France [73] Assignee: Fives Lille Cail, Paris, France [22] Filed: Apr. 13, 1973 [21] Appl. No.: 350,692

[52] US. Cl. 165/114, 165/158, 165/160 [51] Int. Cl. F281 9/10 [58] Field of Search 165/158-161; 122/32, 34

[56] References Cited UNITED STATES PATENTS 1.948.550 2/1934 Vourheis 165/161 X 2.084.743 6/1937 Rathbun 1 1 165/114 2.381.006 8/1945 Scott. .1r.... 165/114 X 2.916.264 12/1959 Rhodes 165/161 X 3.576.178 4/1971 Zmola 122/32 Mar. 19, 1974 Primary Examiner-Charles J. Myhre Assistant Examiner-Theophil W. Streule, Jr. Attorney, Agent, or Firm-Kurt Kelman ABSTRACT A heat exchanger of the tube-and-shell type is equipped with a tube bundle eccentric relative to the upright axis of the shell. The upper part of the tube bundle is enveloped by a cylindrical. coaxial skirt depending from the fixed. upper tube sheet. Steam is admitted to the widest portion of the crescent-shaped, annular-space between the shell and the skirt and deflected to ward the .lower ends of the tubes. The non condensable gases are vented near the axis of the bundle. Partitions in the liquid chambers or heads cause the liquid to be heated to flow downward in the tube nearest the common axis of the bundle and skirt and thereafter alternatingly upward and downward in tubes gradually more remote from the axis of the bundle.

4 Claims, 4 Drawing Figures HEAT EXCHANGEIR This invention relates to heat exchangers, and particularly to a heat exchanger of the tube-and-shell type having fixed tube sheets. i

As the size of tube-and-shell heat exchangers increases, and the number and the length of the tubes in the tube bundle increases, it becomes more difficult to obtain good heat transfer between the steam or other condensable fluid enveloping the tubes and a liquid in the tubes over the entire available tube surface area, and the efficiency of conventional heat exchangers of the afore-described type decreases significantly as their overall capacity increases. This loss in thermal efficiency is particularly significant in upright heat exchangers.

It is the primary object of the invention to provide improved heat transfer between a heating fluid and the fluid to be heated in a tube-and-shell heat exchanger regardless of its dimensions.

With this object and others in view, the invention provides a heat exchanger which has a shell of substantially circular cross section about an upright axis, upper and lower tube sheets sealingly fastened in the shell near respective axially terminal portions of the shell, and tubes having each two axial end portions respectively received in bores of the two tube sheets in sealing engagement. The tubes constitute a tube bundle and seal a vapor chamber axially intermediate the tube sheets from upper and lower liquid chambers axially offset in opposite directions from the tube sheets respectively.

Steam is admitted to a portion of the steam chamber through an inlet adjacent the upper tube sheet. A skirt depends from the upper tube sheet and is interposed between the tube bundle and the shell in the steam chamber. The bundle and the skirt have a common upright axis radially offset from the shell axis in a direction away from the steam inlet in such a manner that the shell and the skirt jointly bound a downwardly open annular space decreasing in radial width in both circumferential directons away from the steam inlet.

A circulating arrangement permits the liquid to be heated to be circulated through the liquid chambers and the tubes. Provisions are made for releasing noncondensable vapors from the steam chamber near the common axis referred to above, and a condensate drain communicates with the steam chamber.

Other features, additional objects, and many of the attendant advantages of this invention will readily be appreciated as the same becomes better understood by reference to the following detailed description of a preferred embodiment of the invention when considered in connection with the appended drawing in which:

FIG. 1 shows a heat exchanger according to the invention in elevational section;

FIG. 2 shows the heat exchanger of FIG. I in top plan view; and

FIGS. 3 and 4 are respective views of the same apparatus respectively taken in section on the lines IlI-III and IVIV.

The illustrated heat exchanger has an upright shell of basically cylindrical shape and circular cross section at right angles to its axis 20. A bundle of upright tubes 12 is arranged in the shell 10, but only one tube has been illustrated for the sake of clarity. The tubes 12 are vertical and their ends are sealingly received in respective bores of two tube sheets 14, 16 fixedly sealed to the inner wall of the shell 10 in axially spaced relationship.

A steam chamber is thus bounded axially by the two tube sheets l4, l6 and radially by the inner wall of the shell 10 and the outer' faces of the tubes 12. The tube bundle has an upright axis 18 radially offset from the shell axis 20, and the shell 10 has a steam inlet 22 in the plane defined by the axes 18, 20, the inlet 22 being spaced from the axis 20 in a direction away from the axis 18, so that the inlet 22 leads into the widest part of the annular space between the tube bundle and the shell 10.

A cylindrical skirt 24 of circular cross section is fixedly fastened in sealing relationship to the upper tube sheet 14 and extends axially downward well below the steam inlet 22. It coaxially envelops the bundle of tubes 12 so that it bounds a crescent-shaped part of the steam chamber near the inlet 22, the radial depth of the chamber part being greatest at the inlet, and decreasing from there in both circumferential directions. The steam admitted through the inlet 22 is led axially downward the free rim of the skirt 24 and it may spread circumferentially without loss of pressure.

A portion of the steam and the light, noncondensable gases rise within the skirt 24 around and between the tubes 12. A venting tube 26 for the noncondensable gases has its orifice below the upper tube sheet 14, within the skirt 24, and near the axis 18. The remainder of thesteam together with the heavy noncondensable. gases descends toward the lower tube sheet 16. The orifice of another venting tube 46 for non-condensable gases is located there near the axis An orifice 48 for releasing condensate from the steam chamber is located near the bottom of the latter, and a drain 50 is provided at the bottom of the shell 10.

The shell includes two covers 28, 30 which respectively axially bound the two liquid chambers and are normally fastened to the cylindrical portion of the shell 10 by means of bolts engaging flanges on the cylindrical shell portion, as is conventional. Integral shafts 32, 34 on the covers 28, 30 permit the covers to be swung out of the illustrated operative position when the bolts are released. The shafts carry rods connected by a strap 36 for convenient simultaneous opening or closing movement of the covers 28, 30 for maintenance purposes.

The liquid chambers bounded by the covers 28, 30 are subdivided by partitions. Three concentric partitions 52a, 52b, 52c divide the upper liquid chamber into a central compartment 54 and three concentric annular compartments 56, 58, 60. The orifice 42 of a feed line for a liquid to be heated communicates with the central compartment 54, and the orifice 44 of a discharge line communicates with the peripheral annular compartment 60.

The lower liquid chamber is similarly divided into three concentric compartments 64, 66, 68 by two partitions 62a, 62b. Gaskets seal the partitions to the associated covers 28, 30. The tube 12 nearest the axis 18 has respective orifices open toward the two central compartments 54, 64, and additional tubes connect the lower central compartment 64 to the upper, innermost, annular compartment 56. This arrangement is continued in an evident manner so that the several compartments jointly with the tubes define a continuous path of liquid flow in alternating axially downward and upward directions through the tubes, the terminal portion of the path being constituted by the compartment 60.

When a stream of liquid admitted through the orifice 42 is to be heated by means of steam supplied to the inlet 22, the steam is distributed circumferentially along the skirt 24 and enters the tube bundle from the bottom rim of the skirt from all radial directions. It flows radially inward into the bundle and axially both upward and downward within and along the bundle. The non-condensable gases are vented near the axis 18 of the bundle, that is, at the end of the flow path followed by the steam so that the probability of steam being entrained by the gases is held to a minimum.

Because of the radial component of steam flow in the tube bundle, the concentration of non-condensable gases increases from the periphery toward the axis of the bundle, and the partial pressure of the steam and its temperature decrease correspondingly. Because the liquid in thermal contact with the non-condensable gases and the coolest portion of the steam in the central tubes is at its lowest temperature, the overall thermal efficiency of the heat exchanger of the invention is high.

It should be understood, of course, that the foregoing disclosure relates only to preferred embodiments of the invention, and that it is intended to cover allchanges and modifications of the example of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the appended claims.

What is claimed is:

l. A heat exchanger comprising:

a. a shell of substantially circular cross section about an upright axis;

b. an upper tube sheet and a lower tube sheet transverse to said axis and sealingly fastened in said shell near respective axially terminal portions of the shell, each sheet being formed with a plurality of axial bores;

c. a plurality of tubes, each tube having two axial end portions respectively received in bores of said tube sheets in sealing engagement, said tubes constituting a tube bundle and sealing a vapor chamber axially intermediate said tube sheets from upper and lower liquid chambers axially offset in opposite directions from said tube sheets respectively;

d. inlet means for admitting steam to a portion of said steam chamber axially adjacent said upper tube sheet;

e. a skirt member depending from said upper tube sheet and being interposed between said tube bundle and said shell in said steam chamber, said bundle and said skirt member having a common upright axis radially offset from the axis of said shell in a direction away from said inlet means, said shell and said skirt member jointly bounding a downwardly open annular space decreasing in radial width in both circumferential directions away from said inlet means; I

f. circulating means for circulating a liquid to be heated through said liquid chambers and said tubes;

g. venting means for releasing non-condensable vapors from said steam chamber near said common axis; and

h. condensate drainage means communicating with said steam chamber.

2. A heat exchanger as set forth in claim 1, wherein said shell includes two covers axially bounding said liquid chambers in respective directions away from the associated tube sheets, each tube having two orifices respectively open toward said liquid chambers, a partition in the upper liquid chamber adjacent the upper tube sheet, said partition separating a portion'of said upper liquid chamber from the remainder of said upper liquid chamber, and said circulating means including feeding means for feeding the liquid to be heated to said portion of the upper liquid chamber, the tube nearest said common axis having an orifice open toward said portion of said upper liquid chamber.

3. A heat exchanger as set forth in claim 2, wherein said shell and said skirt member are substantially cylindrical about said axes respectively, said skirt member having a free rim downwardly offset from said inlet means.

4. A heat exchanger as set forth in claim 3, wherein said partition is member of a group of the innermost first concentric partitions in said upper liquid chamber, said heat exchanger further comprising a second of concentric partitions in said lower liquid chamber, said partitions and said tubes jointly defining a path of liquid flow in alternating axially downward and upward directions through said tubes, said circulating means further comprising discharging means communicating with the terminal portion of said path remote from said feeding means for discharging the heated liquid from said shell. l=

UNETEE STATES PA'EENT @FFECE (IERTHFKCATE @F CU REQ'HQN Patent NO- 3,797-fl566 Dated MM; o K274 lnventofl Paul Credoz et (all It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

:1. M s CZ- On the front page, after if fi/ 1n er 1397 Foreign Application Priority Data 7 Apra l2 ooeooooeocmo'o Signed and sealed this 27th day of August 1974.

(SEAL) Attest:

MCCOY Ma GIBSON, JR. C. MARSHALL DANN Atceeting Officer Commissioner of Patents FORM PO-105O (i0-69) I USCOMM DC B376 p69 u.s. GOVERNMENT PRINTING OFFICE: mes o-ass-su. 

1. A heat exchanger comprising: a. a shell of substantially circular cross section about an upright axis; b. an upper tube sheet and a lower tube sheet transverse to said axis and sealingly fastened in said shell near respective axially terminal portions of the shell, each sheet being formed with a plurality of axial bores; c. a plurality of tubes, each tube having two axial end portions respectively received in bores of said tube sheets in sealing engagement, said tubes constituting a tube bundle and sealing a vapor chamber axially intermediate said tube sheets from upper and lower liquid chambers axially offset in opposite directions from said tube sheets respectively; d. inlet means for admitting steam to a portion of said steam chamber axially adjacent said upper tube sheet; e. a skirt member depending from said upper tube sheet and being interposed between said tube bundle and said shell in said steam chamber, said bundle and said skirt member having a common upright axis radially offset from the axis of said shell in a direction away from said inlet means, said shell and said skirt member jointly bounding a downwardly open annular space decreasing in radial width in both circumferential directions away from said inlet means; f. circulating means for circulating a liquid to be heated through said liquid chambers and said tubes; g. venting means for releasing non-condensable vapors from said steam chamber near said common axis; and h. condensate drainage means communicating with said steam chamber.
 2. A heat exchanger as set forth in claim 1, wherein said shell includes two covers axially bounding said liquid chambers in respective directions away from the associated tube sheets, each tube having two orifices respectively open toward said liquid chambers, a partition in the upper liquid chamber adjacent the upper tube sheet, said partition separating a portion of said upper liquid chamber from the remainder of said upper liquid chamber, and said circulating means including feeding means for feeding the liquid to be heated to said portion of the upper liquid chamber, the tube nearest said common axis having an orifice open toward said portion of said upper liquid chamber.
 3. A heat exchanger as set forth in claim 2, wherein said shell and said skirt member are substantially cylindricaL about said axes respectively, said skirt member having a free rim downwardly offset from said inlet means.
 4. A heat exchanger as set forth in claim 3, wherein said partition is member of a group of the innermost first concentric partitions in said upper liquid chamber, said heat exchanger further comprising a second of concentric partitions in said lower liquid chamber, said partitions and said tubes jointly defining a path of liquid flow in alternating axially downward and upward directions through said tubes, said circulating means further comprising discharging means communicating with the terminal portion of said path remote from said feeding means for discharging the heated liquid from said shell. 